docs: def p_arglist(self, tree):
          ''' V ::= arglist ( V , V )'''
          if type(tree[0].value) == type([]):
              tree.value = tree[0].value + [tree[2].value]
          else:
              tree.value = [tree[0].value, tree[2].value]
          try:
              tree.svalue = "%s,%s"%(tree[0].svalue,tree[2].svalue)
          except AttributeError:
              pass